Pre-IB Biology Ecology Test Study Guide

AP Biology Ecology Test Study Guide

FOOD WEBS, CHAINS

F oo d C h a in A food chain is a single pathway of feeding relationships among organisms in an ecosystem that results in energy transfer.

F oo d W e b Since the feeding relationships in an ecosystem are often too complex to be represented by a single food web, the individual food chains interlink to form a food web. Many consumers eat more than one type of food and more than one species of consumer may feed on the same organism.

TROPHIC LEVELS

An organism’s trophic level indicates the organism’s position in a sequence of energy transfers. Only 10% of energy is transferred to the next trophic level. All producers belong to the first trophic level. Herbivores belong to the second trophic level, and the predators belong to the third level. Most terrestrial ecosystems only have three or four trophic levels, whereas marine ecosystems often have more. BIOTIC AND ABIOTIC FACTORS

B i o t i c F a c t o r s Biotic factors are the living components of the environment. This includes plants and animals. For example, a river ecosystem’s biotic factors would be fish, dragonflies, turtles, bushes, reeds, and trees.

A b i o t i c F a c t o r s Abiotic factors are the nonliving factors – the physical and chemical characteristics of the environment. This includes water, soil, humidity, sunlight, wind, and temperature.

AUTOTROPHS/HETEROTROPHS

A u t o t r o p h s Autotrophs, which include plants and some kinds of protists and bacteria, manufacture they own food. They capture energy and use it to make organic molecules (producers).

H e t e r o t r o p h s Heterotrophs must get energy from food instead of directly from sunlight or other inorganic substances. These are all animals, most protists, all fungi, and many bacteria. They are consumers, getting energy by eating other organisms or organic waste. NICHE CONCEPT – WHAT IT MEANS – EXAMPLE

The specific role, or way of life, of a species within its environment is its niche. This includes the range of conditions that the species can tolerate, the resource it uses, the methods by which it obtains resources, the number of offspring it has, its time of reproduction, and all other interactions within its environment.

The ecological niche of an organism depends not only on where it lives but also on what it does. By analogy, it may be said that the habitat is the organism's "address", and the niche is its "profession", biologically speaking. Odum - Fundamentals of Ecology - W B Saunders 1959

Oak trees absorb sunlight by photosynthesis, absorb water and mineral salts from the soil, provide shelter for animals and other plants, act as a support for creeping plants, serve as a food source for animals, and cover the ground with their dead leaves in the autumn.

CARBON, NITROGEN, WATER CYCLES (GENERAL)

C a r b o n C y c le Photosynthesis and cellular respiration form the basis of the carbon-cycle. In photosynthesis, plants and other autotrophs use carbon dioxide, along with water and solar energy to make carbohydrates. Both autotrophs and heterotrophs use oxygen to break down carbohydrates during cellular respiration. The byproducts of cellular respiration are carbon dioxide and water. Decomposers release carbon dioxide into the atmosphere when they break down organic compounds. Dead organisms and waste products eventually become fossils and fossil fuels. When these are used in auto and factor emissions, carbon dioxide is released into the atmosphere. N i t r og e n C y c le Birth Nitrogen gas makes up about 78% rates, death of the atmosphere. However, most plants rates, and can use nitrogen only in the form of growth rates nitrates. Nitrogen-fixing bacteria for a large transform nitrogen gas into ammonium. population are Then, nitrifying bacteria transform the usually ammonium into nitrites. More nitrifying expressed per bacteria transform nitrites into nitrates, capita. The which are now available of ruse by plants. growth rate Nitrogen can be recycled through can be found ammonification, which turns the ammonia by subtracting from the bodies of dead organisms into the death rate ammonium. Soil bacteria can oxidize this from the birth into nitrates and nitrates, then rate, as denitrification can return to the emigration and atmosphere. This is done by denitrifying bacteria. immigration are assumed to be W a t e r C y c le zero. Water is moved from various reservoirs through the water cycle. Important processes For example: if in the water cycle are evaporation, there are 86 transpiration, condensation, precipitation, and births and 34 percolation. deaths per 1,000 Evaporation adds water as vapor to individuals in a the atmosphere from lakes, rivers, and large population oceans. Transpiration occurs when water in one year... The evaporates from the leaves of plants in birth rate would terrestrial ecosystems. Water leaves the be 86/1,000 atmosphere through precipitation. The water (.086) and the that falls to Earth can then percolate into death rate would the soil and go into the groundwater. be 34/1,000 (.034). The CALCULATING GROWTH RATE growth rate would be .086 - . 034 = .052. To find the number of new individuals that will be added to the population in a year, multiply the per capita growth rate by the total number of individuals in the population. Growth rate can also be calculated through D/ T, which is the difference in population density divided by the difference in time.

CARRYING CAPACITY

The carrying capacity is the number of individuals that the environment can support over a long period of time. This is symbolized by K in the logistic model, which builds on the exponential model while accounting for the influence of limiting factors. As a population size approaches its carrying capacity, the population growth rate slows, and will stop at the carrying capacity. The carrying capacity fluctuates according to the environment.

FACTORS AFFECTING POPULATION GROWTH B i r t h

R a t e , D e a t h R a t e , I mm i g r a t i o n , a n d E m i g r a t i o n Birth and immigration (the movement of individuals into a population) will make a population larger. Death and emigration (the movement of individuals out of a population) will make a population smaller.

D e n s i t y - I n d e p e n d e n t F a c t o r s a n d D e n s i t y - D e p e n d e n t F a c t o r s Environmental disturbances as well as events such as resource limitations are examples of density-independent and density-dependent factors. See DENSITY- DEPENDENT/DENSITY-INDEPENDENT FACTORS for more information.

AGE STRUCTURE GRAPHS

Age structure graphs show the percentage of a population that is in a certain age range. They may also divide this into male and female categories. DENSITY-INDEPENDENT/DENSITY-DEPENDENT FACTORS

D e n s i t y - I n d e p e n d e n t F a c t o r s Density-dependent factors will occur regardless of a population’s density. Such factors come in the form of environmental disturbances such as hurricanes, tornadoes, floods, and drought.

D e n s i t y - D e p e n d e n t F a c t o r s Such factors can be resource limitations such as shortages of food or nesting sites. This is related to how many individuals are in a certain area, because this problem will only occur if there are too many individuals in the area.

COMPETITIVE EXCLUSION PRINCIPLE

The principle of competitive exclusion is used to describe situations in which one species is eliminated from a community because of competition for the same limited resource. This may result when one species uses the limited resource more efficiently than the other species does.

For example, Ecologist George Gause found that the paramecia species P. Aurelia was able to displace P. caudatum because the latter was a more efficient predator of bacteria.

EFFECT OF REMOVING PREDATORS FROM ECOSYSTEM

Removing predators from an ecosystem will seriously disrupt it. For example, when wolves were removed from Yellowstone National Park, the white-tailed deer population grew rapidly, eating all of the grass. With all of the grass eaten, the deer population then died off. The soil then eroded away into the rivers, filling them with sediment, which harmed the life in the rivers. DIFFERENT TYPES OF SYMBIOTIC RELATIONSHIPS AND EXAMPLES

P a r a s i t i s m Parasitism is a relationship in which one individual is harmed while the other individual benefits. This does not usually result in the immediate death of the host, since the parasite depends on the host for survival. Parasites such as aphids, lice, leeches, fleas, ticks, and mosquitoes that live outside of their host are called ectoparasites. Parasites that live inside the host’s body, such as heartworms and disease-causing protists, are endoparasites. Parasites can have a strong negative impact on the health and reproduction of the host.

M u t u a l i s m Mutualism is a relationship in which two species derive some benefit from each other. Some mutualistic relationships are so close that neither species can survive without the other. An example involves the sponge crab (Dromidiopsis dormia) and sponges. The crab will cut out sections of sponge and place them on its back as camouflage. They can also put whole sea anemones on their back. This is helpful for the sponge or sea anemone because they will share in some of the food that the crab eats.

C o mm e n s a l i s m In commensalism, one species benefits and another is not affected. Species that scavenge for leftover food items are often considered to be commensal species. For example, the relationship between Cape buffaloes and cattle egrets is considered to be commensalism. When the buffaloes move to graze, small insects and lizards are forced out of their hiding places. The cattle egrets then feed on these animals. However, the buffaloes generally do not benefit when the cattle egrets are there.

WAYS THAT PLANTS DEFEND THEMSELVES FROM PREDATORS

Plants use protective measures such as thorns and poisons to deter predators. Trees use bark to protect their soft interior and to prevent moisture from seeping out. Certain plants can even fold and unfold their leaves to hide from predators. PRIMARY AND SECONDARY SUCCESSION

P r i m a r y S u cc e ss i o n Primary succession is the development of a community in an area that has not supported life previously, such as bare rock, a sand dune, or an island formed by a volcanic eruption. In primary succession, soil is not initially present. For example, the Canadian Shield was a place where primary succession took place. After a glacier left a stretch of barren bedrock, lichens formed on the rock. When the acids in the lichens washed nutrient minerals from the rock and decomposed lichens formed a thin layer of soil. This allowed grass-like plants to grow. When they decomposed, more organic material was added to the soil. Larger plants began to grow. The Canadian Shield is now densely populated with pine, balsam, and spruce trees.

S e c o n d a r y S u c c e ss i o n Secondary succession is the sequential replacement of species that follows disruption of a community. The disruption may stem from a natural disturbance, such as a forest fire or a strong storm, or from human activity. Secondary succession occurs where soil is already present. In eastern temperate regions, secondary succession typically begins with weeds, such as annual grasses, mustards, and dandelions, whose seeds may be carried to the site by wind or by animals. If no major disturbance occurs, succession in these regions proceeds with perennial grasses and shrubs, continues with trees such as dogwoods, and eventually results in a deciduous forest community. The complete process takes about 100 years.

BIOMES Biomes are areas with distinct vegetation and climates…..see http://www.ucmp.berkeley.edu/exhibits/biomes/ for specifics of each

SPECIES THAT OCCUPY DIFFERENT TERRESTRIAL AND AQUATIC BIOMES S p e c i e s T h a t O cc u p y T e rr e s t r i a l B i o m e s See the Biome Plants and Animals chart at h tt p : // www . s c r i b d . c o m / d o c / 2 1 9 0 66 4 / B i o m e - P l a n t s - a n d - A n i m a l s - C h a r t

S p e c i e s T h a t O cc u p y A q u a t i c B i o m e s Estuary: Atlantic Horseshoe Crab, Ribbed Mussel, Salt Marsh Cordgrass, Common Reed, Diamond Back Terrapin Lakes/Ponds: Red-Necked Grebe, Yellow Perch, Lake Trout, Daphnia, Duckweed, Coontail, Canada Waterweed, Cattails Rivers/Streams: Arrau River Turtle, Common Pufferfish, Red Piranha, Fragrant White Water Lily, Water-Star Grass Freshwater Wetlands: American Alligator, Canadian Pondweed, Spatterdock, Great Blue Heron, Snowy Egrets, Florida Panther

DIFFERENT TYPES OF FORESTS AND GRASSLANDS

T r o p i c a l F o r e s t s Tropical forests occur near the equator, in the tropics. Stable temperatures and abundant rainfall make tropical forests the most productive biome type. They only have a wet and dry season, and are characterized by long wet seasons and tall trees and plants that grow year-round. The treetops form the continuous layer called the canopy, which results in the forest floor being relatively free of vegetation. Small plants live on the branches of tall trees, which are called epiphytes, and include mosses, orchids, and bromeliads. They use other organisms as support, but they are not parasitic because they make their own food. Tropical forests have the highest species richness of all the biomes.

T e m p e r a t e F o r e s t s This biome is characterized by distinct seasons and a moderate climate. Temperate forests can be characterized by the type of tree that is most common, such as coniferous trees, which bear seeds in cones and tend to be evergreen, or deciduous trees, which shed their leaves each year.

T a i g a South of the tundra and north of the temperate region is the taiga, a forested biome dominated by coniferous trees, such as pines, firs, and spruces. It is also called the boreal forest. Plants living in the taiga are adapted for long, cold winters; short summers; and nutrient-poor soil. ZONES OF THE OCEAN

The two zones that measure ocean depth are the photic zone, aphotic zone, and benthic zone. The photic zone is the part of the ocean that receives sunlight and the aphotic zone is where sunlight cannot penetrate. Three zones are relative to the ocean’s edges. The intertidal zone is the area of shoreline that is twice daily covered by water during the high tide and exposed to air during low tide. Farther out is the neritic zone, which extends from the intertidal zone over the continental shelf and to relatively shallow water depths of about 180 meters. Beyond the continental shelf is the oceanic zone, which is the deep water of the open sea. The neritic and oceanic zones are further divided: the open ocean is known as the pelagic zone, and the ocean bottom is known as the benthic zone.

T h e I n t e r t i d a l Z o n e Organisms in the intertidal zone are adapted to periodic exposure to air during low tide. Crabs burrow into the sand or mud, and clams, mussels, and oysters retreat into their shells at low tide.

T h e N e r i t i c Z o n e The neritic zone is the most productive zone in the ocean, since water throughout most of the neritic zone is shallow enough for photosynthesis to occur. Strong currents called upwelling carry nutrients from the ocean bottom and mix them with nutrients contained in runoff from land. These waters are rich in plankton, and coral reefs form in the neritic zones of tropical areas.

MAJOR CHARACTERISTICS OF TERRESTRIAL AND AQUATIC BIOMES

Terrestrial biomes tend to have 3 or 4 trophic levels, while aquatic biomes tend to have more. Additionally, in aquatic biomes, photosynthetic algae are usually the producers.

IMPORTANCE OF DIFFERENT AQUATIC BIOMES

Estuaries serve as breeding ground for migratory birds, and serve as nurseries for fish and other aquatic life. Wetlands function as nature’s filters – some of the sea grass even thrives in polluted water, and cleans it from the environment. The wetlands also soak up water to prevent nearby areas from flooding. GENERAL EFFECTS OF HUMAN IMPACT

O z o n e T h i nn i n g Human-made chemicals have contributed to the destruction of the ozone layer, which will lead to ultraviolet light causing cases of human skin cancer and harming plants and photosynthetic algae.

G l o b a l W a r m i n g High levels of carbon dioxide and certain other gases have caused Earth’s atmosphere to trap more solar energy. This results in rising global temperatures, which could alter rainfall patterns, soil moisture, and sea level around the world. This change could also shift agricultural regions and disrupt both terrestrial and aquatic ecosystems.

A c i d R a in Acid rain is a direct result of fossil fuel combustion. When sulfur dioxide and nitrogen oxides are released into the air, they combine with water to make acidic compounds. The result is acid precipitation. Increased acidity of soil and water causes disease or death in trees, fish, and other organisms.

L a n d a n d W a t e r P o ll u t i o n Humans produce and dispose of waste in the form of sewage and unused material. Many of these chemicals are toxic and some can cause cancer. Dumping sewage into major waterways and using landfills that have not been lined are examples of ways that humans pollute the Earth.

EXAMPLES OF HUMAN IMPACT

E xx o n V a l d e z O i l S p ill When the Exxon Valdez oil tanker crashed into a reef, spilling more than 11 million gallons of crude oil, scientists estimated mass mortalities of 1000 to 2800 sea otters, 302 harbor seals, and unprecedented numbers of seabird deaths estimated at 250,000 in the days immediately after the oil spill.

C a p e C o d E c o s y s t e m I m b a l a n c e Until the 1960s, people harvested the cod, flounder, haddock, and other fish off of Cape Cod at about the same rate that the fish reproduced. When newer fishing methods brought in larger harvests, the fish populations decreased rapidly. Overuse of the resources can seriously disrupt ecosystems. T h e E v e r g l a d e s In the early 20th century, developers could not build on the land since it was too wet. Over time, the developers dug drainage canals to divert water flows toward the ocean to dry out the land. They also planted non-native melaleuca trees because these trees take up large amounts of water from the soil. By the end of the century, half the area’s wetlands had been drained. Ninety percent of the wading birds had disappeared. Sea grass and shrimp nurseries died because the salt concentration had doubled. Fertilizers from agricultural fields poisoned many species and made fish dangerous to eat. The melaleuca trees became an invasive weed.

EXAMPLES OF EXTINCT ORGANISMS

P a ss e n g e r P i g e o n When professional hunters began netting and shooting the birds to sell in the city markets, the number of passenger pigeons began declining rapidly. Since the birds were communal, they were easily netted with baited traps and decoys. Hundreds of thousands of passenger pigeons were killed for private consumption and sale, where they sold for fifty cents a dozen. The last known individual of the species was “Martha,” who died in 1914.

Do do When Portuguese explorers came upon the isle of Mauritius, they were easily able to kill the three-foot, flightless birds for food. When dogs and pigs were introduced to the island, they destroyed dodo nests. Soon afterwards, there were no more dodos to be found.

S t e ll e r ’ s S e a C o w They were hunted for their skin and valuable subcutaneous fat, which was used for food and for oil lamps. Less than 1500 were remaining in 1887, and they were soon wiped out by passing fur traders, sailors, and seal hunters.

ANIMAL BEHAVIOR Behavior All behavior has some genetic basis a. what an animal does and how it 1. capacity for learned behavior is does it inherited b. an animal’s reaction to stimuli 2. behavior is modified by the Innateinborn, present at birth environment in which the animal a. instincts lives b. ex: cats cleaning 3.therefore, both nature and nurture determine an animal’s behavior Kinds of Animal Behavior Fixed-Action Patterns (FAP) 1. innate behavior with unvarying pattern (to natural stimuli) 2. will typically be carried out to completion whether or not the original intent can still be carried out a. elicited by a sign stimulus or releaser, a simple signal that triggers a specific behavioral response 3. exampleEuropean graylag goose a. after mother lays an egg, she will carry out a series of motions to push egg back to nest

b. she will do this with any object that resembles an egg c. if egg is removed after FAP has begin she will continue with motions anyway Learned Behavior (change in behavior due to experience) Habituation 1. learned behavior which allows animal to disregard meaningless stimuli; ignore repeated, irrelevant stimulus 2. ex: gray squirrels respond to alarm calls of other squirrels, but will stop responding if not followed by attack (cry-wolf effect)

Imprinting 1. form of learned behavior closely associated with instinct 2. organism will acquire a specific behavior if an appropriate stimulus is experienced during a critical periodlimited time interval of life of animal, usually within a few hours after birth (or hatching) 3. once acquired, the behavior is irreversible Classical Conditioning 1. associative learninganimals associate one stimulus with another 2. a process in which an animal learns to respond to a stimulus which doesn’t normally elicit that response ex: Ivan Pavlovdog Operant Conditioning (Trial-&-Error Learning) 1. process by which animal learns to associate one behavior with reward or punishment and tends to repeat or avoid that behavior 2. ex: B.F. Skinner a. rats in box with levers b. test animals learned to pull levers that yielded food and avoid those that caused electrical shock Animal Movements Kinesis 1. a randomly directed change in activity rate in response to an environmental stimulus 2. ex: pick up rock, all bugs scurry in response to change in light, temperature, touch, etc. Taxis 1. directed movement in response to a stimulus 2. organism moves towards or away from a stimulus 3. phototaxistowards light Migration 1. seasonal movements of animals over long distances 2. migrants generally make an annual round trip between 2 regions 3. ex: birds, whales, butterflies, fish Communication in Animals used for species recognition, mating, social behavior Chemical 1. pheromoneshormones that are accepted by other individuals; chemical signals secreted by animals that convey information between members of a species; very specific,immediate, but transitory Visual 1. aggression a. catshiss 2. courtship a. male bird plumage

Auditory 1. sounds used to communicate over long distances, water, night Tactile 1. social bonding, infant care, groom, mating Foraging Behavior -optimize feeding -minimize risk of being injured, eaten 1. herds, flocks, schools (aggregations) Biological Rhythms Affect Behavior 1. circadian rhythms-approximately one day a. animals have biological clocks that are set, adjusted, and reset to environmental cues 2. diurnal a. most active during the day 3. nocturnal a. most active during the night 4. crepuscular a. active at dawn or dusk or both Sexual Selection Polygyny 1. favors males; mating with many females 2. male provides little besides supplying sperm Polyandry 1. favors females; mating with several males 2. females receive gifts from many males and elicit help from many to care for their young Monogamy 1. mating with one partner during a breeding season 2. pair bonds form VOCABULARY –not complete  Biodiversity   Biological Magnification   Geosphere   Atmosphere   Fixed Action Pattern  Polyandry (FAP)  Polygyny  Innate Behavior  Monogamy  Habituation  Hydrosphere  Inprinting  Biosphere  Classical Conditioning  Batesian Mimicry  Operant conditioning  Mullerian Mimicry  Taxis  Epiphytes  Kinesis  Eutrophic  Migration  Climax Community  Chemical  Species Richness communication  Survivorship Curves  Visual Communication  K-selected Species  Auditory Communication  r-Selected Species  Tactile Communication  Gross Primary Productivity  Foraging Behavior  Net Primary Productivity  Biological Rhythms  Habitat  Sexual selection  Generalist 